| Reference Type | Journal (article/letter/editorial) |
|---|
| Title | Lead-bearing phyllotungstite from the Clara mine, Germany with an ordered pyrochlore–hexagonal tungsten bronze intergrowth structure |
|---|
| Journal | Mineralogical Magazine |
|---|
| Authors | Grey, I. E. | Author |
|---|
| Mumme, W. G. | Author |
| MacRae, C. M. | Author |
| Year | 2013 (February) | Volume | 77 |
|---|
| Issue | 1 |
|---|
| Publisher | Mineralogical Society |
|---|
| URL | |
|---|
| DOI | doi:10.1180/minmag.2013.077.1.06Search in ResearchGate |
|---|
| Generate Citation Formats |
|---|
| Classification | Not set | LoC | Not set |
|---|
| Mindat Ref. ID | 244375 | Long-form Identifier | mindat:1:5:244375:5 |
|---|
|
| GUID | 0 |
|---|
| Full Reference | Grey, I. E., Mumme, W. G., MacRae, C. M. (2013) Lead-bearing phyllotungstite from the Clara mine, Germany with an ordered pyrochlore–hexagonal tungsten bronze intergrowth structure. Mineralogical Magazine, 77 (1) 57-67 doi:10.1180/minmag.2013.077.1.06 |
|---|
| Plain Text | Grey, I. E., Mumme, W. G., MacRae, C. M. (2013) Lead-bearing phyllotungstite from the Clara mine, Germany with an ordered pyrochlore–hexagonal tungsten bronze intergrowth structure. Mineralogical Magazine, 77 (1) 57-67 doi:10.1180/minmag.2013.077.1.06 |
|---|
| Abstract/Notes | Lead-bearing phyllotungstite from the Clara mine in the central Black Forest, Germany has a formula (Cs0.41)Na0.14K0.05Pb2+2.01Ca0.26[W6+10.87Fe3+3.13O35.75(OH)6.25](O(H2O)3). X-ray diffraction patterns exhibit pseudohexagonal symmetry, but refinement of single-crystal synchrotron data has shown that the true symmetry is orthorhombic, Cmcm, with a = 7.298(1), b = 12.640(2), c = 19.582(4) Å, and that the pseudohexagonal character is due to submicrometre-scale cyclical twinning by rotation about the pseudohexagonal c axis. The structure can be described in terms of an ordered intergrowth, parallel to (001), of (111)py blocks with pyrochlore-type structures, which are ~6 Å in width, and two-layer wide regions with a hexagonal tungsten bronze (HTB) type structure. Caesium atoms occupy 18-coordinate cavities in the HTB regions, and H2O molecules occupy Φ sites in the A2B2O6Φ pyrochlore blocks. The lowering of symmetry from hexagonal to orthorhombic is due to partial ordering of W and Fe in the octahedral B sites and of Pb and vacancies in the A sites of the pyrochlore blocks. The ideal formula for the intergrowth structure (with no vacancies) is C 2A10[B14(O,OH)42]Φ4, where C is the cavity site in the HTB slabs. The mineral has only 21% occupancy of the C site and 25% occupancy of the A site, but full occupancy of the Φ site. There may be some mixing of Cs and H2O between the C and Φ sites. |
|---|
These are possibly similar items as determined by title/reference text matching only.
